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# Copyright (C) 1998-2016 by the Free Software Foundation, Inc.
#
# This file is part of GNU Mailman.
#
# GNU Mailman is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# GNU Mailman. If not, see <http://www.gnu.org/licenses/>.
"""Cook a message's headers."""
import re
from email.header import Header
from email.utils import formataddr, getaddresses, parseaddr
from mailman import public
from mailman.core.i18n import _
from mailman.interfaces.handler import IHandler
from mailman.interfaces.mailinglist import Personalization, ReplyToMunging
from mailman.version import VERSION
from zope.interface import implementer
COMMASPACE = ', '
MAXLINELEN = 78
NONASCII = re.compile('[^\s!-~]')
@public
def uheader(mlist, s, header_name=None, continuation_ws='\t', maxlinelen=None):
"""Get the charset to encode the string in.
Then search if there is any non-ascii character is in the string. If
there is and the charset is us-ascii then we use iso-8859-1 instead. If
the string is ascii only we use 'us-ascii' if another charset is
specified.
"""
charset = mlist.preferred_language.charset
if NONASCII.search(s):
# use list charset but ...
if charset == 'us-ascii':
charset = 'iso-8859-1'
else:
# there is no non-ascii so ...
charset = 'us-ascii'
return Header(s, charset, maxlinelen, header_name, continuation_ws)
def process(mlist, msg, msgdata):
"""Process the headers of the message."""
# Set the "X-Ack: no" header if noack flag is set.
if msgdata.get('noack'):
del msg['x-ack']
msg['X-Ack'] = 'no'
# Because we're going to modify various important headers in the email
# message, we want to save some of the information in the msgdata
# dictionary for later. Specifically, the sender header will get waxed,
# but we need it for the Acknowledge module later.
msgdata['original_sender'] = msg.sender
# VirginRunner sets _fasttrack for internally crafted messages.
fasttrack = msgdata.get('_fasttrack')
# Add Precedence: and other useful headers. None of these are standard
# and finding information on some of them are fairly difficult. Some are
# just common practice, and we'll add more here as they become necessary.
# Good places to look are:
#
# http://www.dsv.su.se/~jpalme/ietf/jp-ietf-home.html
# http://www.faqs.org/rfcs/rfc2076.html
#
# None of these headers are added if they already exist. BAW: some
# consider the advertising of this a security breach. I.e. if there are
# known exploits in a particular version of Mailman and we know a site is
# using such an old version, they may be vulnerable. It's too easy to
# edit the code to add a configuration variable to handle this.
if 'x-mailman-version' not in msg:
msg['X-Mailman-Version'] = VERSION
# We set "Precedence: list" because this is the recommendation from the
# sendmail docs, the most authoritative source of this header's semantics.
if 'precedence' not in msg:
msg['Precedence'] = 'list'
# Reply-To: munging. Do not do this if the message is "fast tracked",
# meaning it is internally crafted and delivered to a specific user. BAW:
# Yuck, I really hate this feature but I've caved under the sheer pressure
# of the (very vocal) folks want it. OTOH, RFC 2822 allows Reply-To: to
# be a list of addresses, so instead of replacing the original, simply
# augment it. RFC 2822 allows max one Reply-To: header so collapse them
# if we're adding a value, otherwise don't touch it. (Should we collapse
# in all cases?)
if not fasttrack:
# A convenience function, requires nested scopes. pair is (name, addr)
new = []
d = {}
def add(pair): # noqa: E301
lcaddr = pair[1].lower()
if lcaddr in d:
return
d[lcaddr] = pair
new.append(pair)
# List admin wants an explicit Reply-To: added
if mlist.reply_goes_to_list == ReplyToMunging.explicit_header:
add(parseaddr(mlist.reply_to_address))
# If we're not first stripping existing Reply-To: then we need to add
# the original Reply-To:'s to the list we're building up. In both
# cases we'll zap the existing field because RFC 2822 says max one is
# allowed.
if not mlist.first_strip_reply_to:
orig = msg.get_all('reply-to', [])
for pair in getaddresses(orig):
add(pair)
# Set Reply-To: header to point back to this list. Add this last
# because some folks think that some MUAs make it easier to delete
# addresses from the right than from the left.
if mlist.reply_goes_to_list is ReplyToMunging.point_to_list:
i18ndesc = uheader(mlist, mlist.description, 'Reply-To')
add((str(i18ndesc), mlist.posting_address))
del msg['reply-to']
# Don't put Reply-To: back if there's nothing to add!
if new:
# Preserve order
msg['Reply-To'] = COMMASPACE.join(
[formataddr(pair) for pair in new])
# The To field normally contains the list posting address. However
# when messages are fully personalized, that header will get
# overwritten with the address of the recipient. We need to get the
# posting address in one of the recipient headers or they won't be
# able to reply back to the list. It's possible the posting address
# was munged into the Reply-To header, but if not, we'll add it to a
# Cc header. BAW: should we force it into a Reply-To header in the
# above code?
# Also skip Cc if this is an anonymous list as list posting address
# is already in From and Reply-To in this case.
if (mlist.personalize is Personalization.full
and mlist.reply_goes_to_list is not # noqa: W503
ReplyToMunging.point_to_list
and not mlist.anonymous_list): # noqa: W503
# Watch out for existing Cc headers, merge, and remove dups. Note
# that RFC 2822 says only zero or one Cc header is allowed.
new = []
d = {}
for pair in getaddresses(msg.get_all('cc', [])):
add(pair)
i18ndesc = uheader(mlist, mlist.description, 'Cc')
add((str(i18ndesc), mlist.posting_address))
del msg['Cc']
msg['Cc'] = COMMASPACE.join([formataddr(pair) for pair in new])
@public
@implementer(IHandler)
class CookHeaders:
"""Modify message headers."""
name = 'cook-headers'
description = _('Modify message headers.')
def process(self, mlist, msg, msgdata):
"""See `IHandler`."""
process(mlist, msg, msgdata)
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